Gray-scale ultrasonic properties of the normal and inflamed pancreas.

Eighty-seven examinations of the pancreas in 52 patients with acute or chronic pancreatitis and 31 examinations in 31 normal subjects were reviewed. Demonstration of the portal and splenic veins served as a guidepost to the pancreas. The normal pancreas was indistinguishable from the surrounding tissues in a substantial minority of examinations, and the ultrasonic characteristics of the normal pancreas were quite variable. Acute pancreatitis was found to be characterized by swelling, loss of internal echoes, and loss of distinction between the pancreas and splenic vein. In 50% of patients with chronic inactive pancreatitis, the pancreas could not be identified. Ultrasound should precede endoscopic retrograde cholangiopancreatography whenever a pseudocyst might be present.